Vapor seal unit

ABSTRACT

A tank for gasoline or other volatile liquid is provided with a vent pipe having a vapor seal device communicating therewith and located above the level of the tank. The vapor seal device embodies a normally closed chamber having flexible walls and a passage communicating with the lower portion of the chamber serves to permit liquid accumulating in the chamber to return to the vent pipe and tank. Valve means are also provided for limiting the difference in pressure between the interior and exterior of the chamber.

Hfiited States Patent [191 Panacek 1 1 VAPOR SEAL UNIT Anton F. Panacek, Harbourton Woodsville Rcl., Box 191, RD. 1, Lambertville, NJ. 08530 [22] Filed: Mar. 29, 1974 [21] Appl. No: 456,147

[76] lnventor:

[521 U.S. Cl. 220/85 VR; 138/30; 220/85 B [51] Int. Cl. B65D 25/00; F16L 55/04 [58] Field of Search .1 138/30; 220/209, 368, 18,

220/85 VR, 85 VS, 85 B, 202/185 R, 190, 202/191; 55/319, 423. 466

[56] References Cited UNITED STATES PATENTS 2,583.062 1/1952 Riboud 220/85 VS 2.946.475 7/1960 Rockelman 220/18 [451 July 1,1975

3,461,914 8/1969 Sugimura et al 138/30 Primary Examiner-John W. Huckert Assistant Examiner Charles Gorenstein Attorney, Agent, or FirmSperry and Zoda [57] ABSTRACT A tank for gasoline or other volatile liquid is provided with a vent pipe having a vapor seal device communicating therewith and located above the level of the tank. The vapor seal device embodies a normally closed chamber having flexible walls and a passage communicating with the lower portion of the chamber serves to permit liquid accumulating in the chamber to return to the vent pipe and tank. Valve means are also provided for limiting the difference in pressure between the interior and exterior of the chamber.

2 Claims, 1 Drawing Figure VAPOR SEAL UNIT FIELD OF INVENTION It is usual practice to provide gasoline tanks and other tanks for volatile liquid with a vent pipe for preventing the build up of pressure within the tank when it is being filled with liquid and when vapors within the tank expand and contract with changes in temperature. However, when the liquid within the tank is gasoline or other volatile liquid considerable loss is encountered due to evaporation especially during warm weather or as wind blows over the vent pipe so as to reduce the pressure therein and cause vapors to be drawn off from the tank. Furthermore, under some conditions when filling the tank or at other times liquid may be forced up from the tank through the vent pipe so as to be discharged therefrom creating a dangerous fire hazard.

It has been suggested heretofore that the vent pipe connected to such a tank may be provided with means for trapping liquid passing outward through a vent pipe as exemplified by U.S. Pat. No. 2,946,475 but the construction thus provided does not serve as a vapor seal with the result that evaporation losses can still take place freely. In the US. Pat. No. 2,583,062 a construction is disclosed which serves to seal the tank but the device is relatively complicated and is not adapted to be applied to the conventional vent pipe of a gasoline tank in a gasoline station or on a farm or elsewhere.

In accordance with the present invention a simple and economical form of vapor seal and liquid trap is provided which is adapted to be applied to a conventional form of vent pipe for a tank to prevent or reduce the loss of volatile vapors from the tank. The construction further serves to maintain the pressure within the tank within predetermined limits and in addition is constructed so that vapors condensed within the device or otherwise accumulating therein will be returned to the tank whereby losses are reduced to a minimum and substantial economies are effected in the storage of liquids.

These results are attained by providing a normally closed chamber communicating with the vent pipe of a tank with the chamber having one or more movable or flexible walls permitting expansion and contraction to vary the volume of the chamber in response to evaporation or changes in pressure of the vapors within the tank. The vapors entering the chamber during the daytime or when the temperature of the tank increases for any reason are retained within the chamber and thereafter condense into liquid at nighttime or when the temperature falls. The resulting liquid together with any entrained or other liquid which enters the chamber is thus returned to the vent pipe for delivery back to the tank. In actual practice, the device disclosed herein, when applied to a 235 gallon tank containing gasoline. reduced evaporation losses by about 50 gallons within a period of four months.

THE DRAWING The drawing is a diagrammatic illustration of a typical embodiment of the present invention applied to a tank.

PREFERRED EMBODIMENT In that form of the invention chosen for purposes of illustration in the drawing the vapor seal device 2 is applied to the vent pipe 4 ofa tank 6 to which liquid may be supplied through an inlet 8. The device 2 is secured to an upper portion of the vent pipe so as to be located above the level of the tank. As shown the vapor seal device embodies an upper member 10 and a lower member 12 which are secured to the vent pipe 4 by welding or otherwise so as to assure an air-tight seal therewith. A flexible member 14 cooperates with the upper and lower members 10 and I2 and serves to form the side walls of a closed chamber 16 which communicates with the vent pipe through an opening 18 near the upper portion of the chamber and further is provided with a drain passage 20 formed in the lower member 12 for returning liquid from the chamber 16 to the vent pipe through openings 22.

The side wall forming member 14 is formed of flexible material such as neoprene or the like which will not be adversely affected by the vapors of gasoline or other liquid being stored in the tank 2. Further, the material of which the side walls of the chamber is formed may be elastic and is designed and arranged to be movable in response to changes in pressure of the vapors within the tank and chamber. Thus, as shown in full lines in the drawing the member 14 may be flexed inward when the pressure of the vapor within the chamber 16 is below ambient air pressure but is movable outward to the expanded position shown in dotted lines when the pressure of the vapors within the tank and chamber 16 is higher than the pressure of the ambient air on the exterior of the chamber.

The vapor seal device further is provided with means for preventing the development of excessive differences in pressure within the assembly which might interfere with the normal operation and use of the tank. For this purpose a check valve 24 is connected to the vent pipe and is constructed or adjusted to relieve the pressure developed within the tank when it is being filled by the introduction of liquid through the filling opening 8. In a similar way the check valve 24 will serve to relieve excessive pressure which may build up within the tank and chamber 16 of the vapor seal device when abnormal evaporation takes place and the permissible expansion of the side walls of the chamber 16 takes place so as to create the danger of rupture of the flexible material of which the side wall member is formed.

An additional check valve 26 is mounted in the upper member I0 of the vapor seal device 2 and is constructed or adjusted to respond to a decrease in pressure within the chamber 16 beyond that permitted by flexing of the side wall member 14. The check valve 26 thus operates to permit the entry of air into the chamber for passage to the vent pipe 4 and tank 6 as liquid is drawn from the tank for use and when the pressure within the chamber 16 is excessively reduced for any reason.

The construction thus provided is adapted to be applied to existing storage tanks for gasoline or other volatile liquids having a vent pipe and serves to prevent or materially reduce evaporation losses which would otherwise occur. It serves to seal the vent pipe during normal storage conditions without interfering with the normal filling and emptying of the tank. On the other hand when evaporation of the liquid takes place the vapors which otherwise would escape to the atmosphere are retained in the normally closed chamber and a limited but predetermined pressure is built up within the chamber and transmitted to the tank itself to reduce the rate of evaporation of the liquid to at least some extent. At the same time any liquid which may pass up the vent pipe due to any bubbling or surging within the tank when it is filied or at any other time will be caught and retained in the chamber 16. In addition, upon cooling of the chamber at nighttime or when the temperature falls for any reason the vapors within the chamber are condensed and allowed to drain back through the passages 20 and openings 22 to the vent pipe for return to the tank. In this way evaporation losses are reduced to a minimum and very substantial savings are effected in the storage of liquids While the construction shown in the drawing and described above is preferred and has proven very practical in use. it will be apparent that numerous changes and variations may be made in the form construction and arrangement of the elements of the combination. ln view thereof it should be understood that the embodiment of the invention disclosed herein is intended to be illustrative only and is not intended to limit the scope of the invention.

I claim:

1. In combination with a tank for volatile liquid having an inlet and a vent pipe, a vapor seal device located above said tank and embodying a normally closed chamber adapted to receive and retain vapors arising from said tank there being a passage from said vent pipe opening into the upper portion of said chamber for the delivery of vapors to the chamber and a return passage leading from the lower portion of said chamber to said vent pipe for return of liquid to the tank, a wall of said chamber being formed of flexible material and subjected exteriorly to atmospheric pressure which being subjected interiorly to the pressure of vapors in said vent pipe, said wall being movable in response to variations in such pressures to vary the capacity of said chamber a check valve communicating with said chamber and operable to relieve excessive pressure developed in said chamber and a second check valve op- 5 erable to admit ambient air to said chamber upon reduction in pressure in the chamber below a predetermined minimum whereby rupture of the flexible material forming said wall is prevented 2. The combination as defined in claim 1 wherein said chamber embodies fixed upper and lower members secured to the vent pipe and the side walls of said chamber are formed of flexible material secured to said upper and lower members, 

1. In combination with a tank for volatile liquid having an inlet and a vent pipe, a vapor seal device located above said tank and embodying a normally closed chamber adapted to receive and retain vapors arising from said tank, there being a passage from said vent pipe opening into the upper portion of said chamber for the delivery of vapors to the chamber and a return passage leading from the lower portion of said chamber to said vent pipe for return of liquid to the tank, a wall of said chamber being formed of flexible material and subjected exteriorly to atmospheric pressure which being subjected interiorly to the pressure of vapors in said vent pipe, said wall being movable in response to variations in such pressures to vary the capacity of said chamber, a check valve communicating with said chamber and operable to relieve excessive pressure developed in said chamber and a second check valve operable to admit ambient air to said chamber upon reduction in pressure in the chamber below a predetermined minimum whereby rupture of the flexible material forming said wall is prevented.
 2. The combination as defined in claim 1 wherein said chamber embodies fixed upper and lower members secured to the vent pipe and the side walls of said chamber are formed of flexible material secured to said upper and lower members. 